Selection of valve electric ACTUATOR
In pipeline engineering, the correct selection of electric valves is one of the guarantee conditions to meet the requirements of use. If the electric valve used is improperly selected, it will not only affect the use, but also bring adverse consequences or serious losses. Therefore, the electric valve should be correctly selected in the pipeline engineering design.
The self-adjusting electric device adopts a dedicated three-phase asynchronous and single-phase motor-driven actuator, and there are two forms:
Linear travel electric actuators and quarter-travel electric actuators.
1) Receive: DC0~10mA, 4~20mA, 0~10V signal.
2) Send out: DC4~20mA.
Can be matched with various regulating valves.
The two-wire control type electric valve refers to the electric device equipped with the electric valve, and its control wire adopts the control form of at least 2 wires. If you control multiple units (2 units or more), you need (n+1) wires, and “n” is the number of electric valves to be controlled, so it is also called (n+1) control mode. The control form of this electric valve is suitable for multiple remote control. The characteristics of this control form are that it can save a lot of wiring costs, and it is also beneficial to improve the control reliability of the electric valve. Because the number of wires used is small, and the signal adopts the pulse mode, it can avoid and reduce the pressure caused by the wiring resistance. The malfunction of the electric device caused by the drop and the capacitance between the wirings. Compared with the ordinary type, the two-wire control type has the following characteristics:
①The wiring is simple, saving wires and wiring time;
②It is more suitable for long-distance operation, and the control distance is better than 800m;
③It has an overvoltage protection circuit, which can avoid malfunction caused by line overvoltage or lightning strike;
④It has a wrong judgment loop, which can timely judge and find the wrong action caused by a certain reason;
⑤ Can be networked with computers, and can directly receive computer signals for work.
The electric valve used in general working conditions has a single speed of opening and closing the valve during working operation, and the speed does not change. At the moment of opening or closing the valve, it is prone to failure and affects normal work. The two-speed control type electric valve is completed by two speeds during each process of opening and closing.
Assuming that the full stroke of the valve is 100%, the valve operates at low speed during the opening (0-10%) stroke, and the rest of the stroke is at high speed. When the valve is closed, the stroke from (100%-10%) is high-speed operation, and from (10%-0) is low-speed operation. The switching points for low-speed and high-speed operation can be adjusted according to actual operating conditions. The speed conversion is done automatically.
